Prevent '-u' when operating on GPT formatted disks, as the

equivalent 'update' editing command already is.

Avoids the destruction of the GPT when the preventative MBR
is overwritten with the default MBR.

ok deraadt@

diff --git a/sbin/fdisk/fdisk.c b/sbin/fdisk/fdisk.c
index c9b58c7..2dd0704 100644 (file)
--- a/sbin/fdisk/fdisk.c
+++ b/sbin/fdisk/fdisk.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: fdisk.c,v 1.144 2022/04/24 12:13:37 krw Exp $ */
+/*     $OpenBSD: fdisk.c,v 1.145 2022/05/12 11:04:27 krw Exp $ */
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -187,6 +187,8 @@ main(int argc, char *argv[])
                        Xwrite(NULL, &mbr);
                break;
        case INIT_MBRBOOTCODE:
+               if (GPT_read(ANYGPT) == 0)
+                       errx(1, "-u not available for GPT");
                if (MBR_read(0, 0, &mbr))
                        errx(1, "Can't read MBR!");
                memcpy(mbr.mbr_code, default_dmbr.dmbr_boot,